Abstract
The aim of the present study was to explore the dynamic relationship between Notch and non‑alcoholic fatty liver disease (NAFLD), both in vitro and in vivo. The LX2, Huh7 and MIHA hepatic cell lines were used to establish a cell steatosis model induced by palmitic acid (PA) at different concentrations (0.1, 0.25 and 0.5 mM). Cell proliferation and migration were assessed using a 5‑bromo‑2'‑deoxyuridine kit and a wound healing assay. The dosage of 0.25 mM PA for 36‑48 h treatment was chosen for subsequent experiments. Steatotic cells were identified by Oil Red O staining. Feeding mice a methionine‑choline‑deficient (MCD) diet is known induce a model of NAFLD, compared with a methionine‑choline‑sufficient (MCS) diet. Therefore, Notch family mRNA expression was evaluated in the liver of MCD‑fed mice at varying time points (days 5, 10, 21 and 70) using reverse transcription‑quantitative PCR. Notch expression levels were also assessed in cell lines at 12, 24, 36 and 48 h after PA treatment. Notch signaling molecules changed in the PA or MCD model over time. In vitro, the mRNA levels of Notch1, ‑2 and ‑4 increased in all cell lines after 12‑h PA treatment. At 24 h, these genes were upregulated only in LX2 cells, while showing a 'down‑up' pattern in MIHA cells (i.e. these genes were downregulated at 24 h but upregulated at 36 h). However, expression of Notch1, ‑2, ‑3 and ‑4 mRNA rose significantly in the early stage (day 10) of NAFLD. At week 3, the levels of Notch1 and ‑2 were higher in the MCD group than in the MCS group, while the reverse was observed for Notch3 and ‑4. Expression of these four genes increased again in the late stage (day 70) of NAFLD. Therefore, these results indicated that Notch family members Notch1‑4 were involved in the development of NAFLD and played an important role in steatosis in this model.